Metal drawing process



June 6, 1944. B. F. BUTLER EIAL METAL DRAWING PROCESS Filed Sept. 29} 1945 2 Sheets-Sheet 1 R a; M00 Va R ND u w 1; m m4 R M Z Q6: Y 3 M OF SQLUTION SAT U RATE D CONCENTRATION June 1944- B. F. BUTLER EIAL 2,350,491 v METAL DRAWING PROCESS Filed Sept. 29, 1943 2 Sheets-Sheet 2 INVENTORS ficm/nmllv 80729 BY 060)? A blxpLfA Patented June 6, 1944 UNITED STATES 2,350,491 PATENT OFFICE I 2,350,491 I METAL DRAWING rnocnss Benjamin F. Butler, Westport, and Edgar A. Birdler, Bridgeport, Conn., assignors to Remington Arms Company, Inc.

Fig. 4 represents the cup of Fig. 3 after it has been passed through another die.

Fig. 5 represents the cup of Fig. 4 after it has been passed through a third drawing die.

Fig. 6 represents a cross sectional view of a finished case.

Fig. 7 is a fragmentary view of a punch and die.

Fig. 8 is a perspective view of one form of apparatus which may be used.

Fig. 9 is a sectional elevation of another form of apparatus which may be used.

Fig. 10 is a sectional elevation of another form of apparatus which may be used.

Fig. 11 is a graph showing the relation between particle size and concentration of solution.

In the manufacture of cartridge cases the first operation is usually to cut a disc or blank (Fig. 1) from a flat strip of metal and then to cut this disc to the form shown in Fig. 2. This is done in a single press using a blanking and cupping Bridgeport, Comm, a corporation of Delaware Application September 29, 1943, Serial No. 504,254

17 Claims. ('01. 205-8) This invention relates to the manufacture of die or may be done in two presses or operations. ferrous metal articles by mechanical working or The cup of Fig. 2 is passed through succeeding plastic deformation, such as drawing, and is pardies by means of a punch 20, such as shown in ticularly applicable to shaping when the tem- Fig. 7, until the proper dimensions are secured. perature of working is relatively low. One im- 5 The die is indicated at 22, die holder at 23, and portant use of the invention is in the drawing of the piece to be drawn is at 24. It is to be noted steel cartridge cases or ammunition components. that there is considerable reduction of the wall In the manufacture of ammunition componthickness in each operation, which requires a ents, and especially cartridge cases, the surface large amount of work to be performed upon the must be free from imperfections such as 10 case in the drawing operations. The case can be scratches, because these imperfections are potenfinished after the drawing is completed by plactial points of failure in the finished shell. The ing the desired extraction groove 2! and other cartridge case is subjected to extremely high conventional features thereon, such as shown in pressures upon firing and may be as high as Fig. 6. The example shown is a centerilre case 50,000 pounds per square inch in the conventional similar to the caliber .45 cartridge with the thiclscaliber .30 cartridge. The life of the drawing die nesses slightly exaggerated. If a rimfire case is is also an important factor in the quantity proto be produced, the base is folded over in a conduction of ammunition. A drawing aid must be ventional manner to produce the rim in which provided which will give long die lifeand as near the priming mixture is placed.

perfect surfaces on the drawn article as possible. 20 In. the present invention, the case or strip be- The size of the case is critical so that if the die fore drawing, is subjected to hydrogen sulphide. wears rapidly, it will be necessary to frequently This will form a coating thereon which for some change dies so as to maintain the correct dimenunknown reason allows the drawing of steel comsions. The characteristics of brass usually em-- ponents without undue wear on the drawing die D yed in t e manu a tu f Cartridge Cases are and with excellent surfaces on the drawn comsuch that the metal will draw properly with a ponents. The surface can be subjected to hydroconventional lubricant but this is not so with gen sulphide by placing the article in water and steel. bubbling hydrogen sulphide through the water,

n the Present invention a process and dreW- such as shown in Fig. 8, or the article can be ing aid is emp oyed which makes use of the remoistened and then subjected to the hydrogen action product of hydrogen sulphide in contact sulphide I ith case, an amorphous or with iron. These and other je of the invencolloidal particle size coating is formed on the tion will beco pp from the following article. This coating is dark and is not firmly description and the drawings. bonded to the surface.

In the drawings: 5 As the water on the surface is subjected to Fig. 1 represents a disc. hydrogen sulphide gas, the gas will be absorbed Fi 2 represents a up d from the discthereby. The solubility of hydrogen sulphide gas Fi 3 rep the p of 2 after it has in water is low, the saturated solution at 25 C. been passed through a drawing e- 40 being .2 normal and the higher the temperature the less the solubility. It can be theorized that the following primary ionization takes place:

A secondary ionization then takes place as shown HS- H+ +S- i The value of the ionization content of the sulphide ion in a saturated solution at 25 C. is given as 1.2 10 as compared to 0.9x10- moles per liter for the hydrogen ion concentration. It is thus apparent that the conditions are such that the particle size of the ferrous sulphide as the result of the reaction of 'the iron ion and the sulphide ion will be in the colloidal range. This is indicated by the graph shown in Fig. 11 giving the relation between particle size and concentration, said graph being based on Von Weimarns law.

Also the iron solubility will be low because of the low hydrogen ion-concentration.

The precipitate of ferrous sulphide is hydrous which may be one of the reasons-for its emciency as alubricant. The coating appears to be better 5 if'the water is changed frequently or possibly kept aerated.

Following this treatment, it is desirable to subject the surface to a lubricant or other material which will prevent oxidation thereof. It was found that if the surface was left exposed to the air for as little asfive minutes, that rusting might occur which would interfere with the subsequent drawing operations. The time after sulfidation in which it is desirable to treat the surface to prevent oxidation, of coursepwill depend upon the conditions and may be longer or shorter than five minutes. The treatment to prevent oxidation of the coating formed by sulfidationmay or may not have a lubricant combined therewith.

It was also found that if the article had the surface thereof pitted before sulfidation, that excellent drawing properties would result. The pitting may be obtained by treating the case with a solution containing ferric ions in sufficient quantities to attack the surface properly. One solution is that composed principally of water and ferric sulphate. One theory for the chemical action which takes place is that there is a reduction of the ferric ion to the ferrous ion by the loss of one charge. At the sometime there is an oxidation reaction of the metallic iron to the ferrous ion. This may be represented by the following formula:

There is thus a dissolution of the metal on the surface of the case. When ferric sulphate is used, the exterior surface is pitted uniformly. In the lubricating or oxidation preventing treatment any of the well known drawing lubricants may be used. One of these may be composed substantially as follows:

Per cent Soap 11.8 Mineral matter 0.4 Free fatty acid (as oleic acid) 9.8 Water 58.0 Mineral oil (or other oils) 20.0

Per cent Rosin 4.75 N83PO4 2.8 Na4SiO4 25.2 NaOH 50.0 N Water 17.25)

In this case the alkali solution may be heated to 180 F. and the strips placed therein for about three minutes.

2. The strips are then rinsed in hot water.

3. The surface is subjected to a ferric sulphate solution which may bemade by using 5% to 15% (10% being preferable) oi Ferrisul in water maintained at -180", being preferable. The strips are placed in the Ferrisul solution for a period of time of five to fifteen minutes although six minutes appears to be the preferable amount. "Ferrisul is a commercially avaliable product containing about 90% ferric sulphate.

4. The strips are scrubbed and rinsed to remove all traces of the ferric sulphate solution.

5. The strips are sulfldated in any of the manners set forth hereafter.

6. The articles are rinsed.

7. The articles are lubricated with a substance such as that described previously. The articles may also have lard oil placed thereon or lard oil may be used without any other lubricant. The articles are then drawn as described previously.

Several forms of apparatus may be used for sulfidating the strip. One form is shown in Fig. 9 wherein the tank 25 contains water 26 and has a shaft 21 with a suitable handle 28 located at the exterior of the tank. The shaft 21 has a bracket 29 with clamps 30 thereon for clamping the steel strips 3| in place. The inverted container 32 has hydrogen sulphide gas introduced therein in any suitable manner. The handle 28 is turned to bring the steel strip 3i into the position shown in dotted lines at 33. The strip is thus passed through the water and becomes moistened before it is subjected to the hydrogen sulphide gas. At temperatures of about room, a coating is produced in as little as 15 seconds but it is to be understood that the time will vary in accordance with many factors, such as cleanliness of the strip, purity of the gas, etc.

Another form of apparatus is shown in Fig. 10..

wherein there is a tank 34 containing water 35. The container 36 is supported or allowed to float on the water and hydrogen sulphide gas is introduced into the interior thereof. An endless conveyor belt 3'! having means to engage the articles is used to carry the articles through the water and to the hydrogen sulphide gas in the container 36. The articles may be removed from the belt at 38 in any suitable manner.

An apparatus is shown in Fig. 8 which may be used to immerse the steel strips in water through which hydrogen sulphide gas is'bubbled. A sourcev of hydrogen sulphide gas is indicated at 39. A valve arrangement 40 controls the flow of gas through pipe 4| and into the distributing tube 42 at the bottom of tank 43, tank 43 having water therein. 'The strips are placed in the water through the opening 44 in the hood over the top of the tank 43 and tank 45. A blower is attached to pipe 41 for the purpose of removing the gas through passage 46- as it comes from the surface of the Water in tank 43. The pipe 41 and blower attached thereto may be arranged to pass said gas through a purifier before exhausting to a suitable place.

Any gas which is not removed by 46 and 41 will be exhausted through the upper hood 4!! and by a suitable blower attached to pipe 49. The tank 45 serves as a rinsing tank and the steel strips may be removed from tank 43 upon completion of sulfidation and immediately be transferred to tank 45 for rinsing purposes. It is apparent that other forms of apparatus may be used and that those shown are merely exemplary.

'By the present invention, steel articles, such as ammunition components may be subjected to deep drawing operations with long die life and excellent. drawn surfaces.

What is claimed is:

1. In the drawing of a ferrous metal article, the method comprising the steps of producing an amorphous coating on said article by subjecting said article to hydrogen sulphide, and then shaping said article by drawing.

2. In the shaping of a ferrous metal article, the method comprising the steps of producing a coating on said article by subjecting said article to hydrogen sulphide in the presence of water, and then shaping said article by drawing.

3. In the shaping of a ferrous metal article, the method comprising the steps of producing a coating of colloidal particle size on said article by subjecting said article to hydrogen sulphide, and then shaping said article by drawing.

4. In the shaping of a'ferrcus metal article, the method comprising the steps of producing a drawing aid coating on said article by sub- J'ecting said article to hydrogen sulphide in the presence of water, treating said coating to substantially prevent oxidation, and then shaping said article by drawing.

5. In the shaping of a ferrou metal article, the method comprising the steps of producing a drawing aid coating on said article by subjecting said article to hydrogen sulphide in the presence of Water, placing a lubricant on said coated article, and then shaping said article by drawing.

6. In the shaping of a ferrous metal article, the method comprising the steps of placing a coating of colloidal particle size thereon by subjecting said article to hydrogen sulphide in the presence of water, placing a lubricating compound on said article immediately after subjecting to the hydrogen sulphide, and then shaping said article by drawing.

7. In the drawing of a ferrous metal article, the method comprising the steps of subjecting the surface of said article to water, subjecting said moistened article to hydrogen sulphide, and then shaping said article by drawing.

8. In the drawing of a ferrous metal article, the method comprising the steps of subjecting the surface of said article to water, forming a drawing aid coating thereon having a colloidal particle size by exposure to hydrogen sulphide, applying a lubricant to said coated article, and then shaping said article by drawing.

9. In the drawing of a ferrous metal article, the method comprising the steps of forming a colloidal drawing aid coating thereon by placing the article in a bath through which hydrogen sulphide is bubbled, and then shaping said article by drawing.

10. In the shaping of a ferrous metal article, the method comprising the steps of placing thereon a drawing aid which is the reaction product of hydrogen sulphide and the iron of said article, and then subsequently shaping said article.

11. In the shaping of a ferrous metal article,

the method comprising the steps of pitting the surface of said article, placing a'drawing aid thereon which is the reaction product of hydrogen sulphide and the iron of said article, and then subsequently shaping said article by drawing.

12. In the shaping of a ferrou metal article. the method comprising the steps of pitting the surface of said article, placing a drawing aid thereon which is the reaction product of hydrogen sulphide and the iron of said article in the presence of Water, and then subsequently shaping said article by drawing.

13. In the shaping of a ferrous metal article, the method comprising the steps of pitting the surface of said article, subjecting the surface of said article to hydrogen sulphide in the presence of water, lubricating said surface immediately thereafter, and then shaping said article by drawing.

14. In the drawing of a ferrous metal article,

the method comprising the steps of subjectingthe surface to be drawn to a solution containing ferric ions, placing a drawing aid thereon which is the reaction product of hydrogen sulphide and the iron of said article, and subsequently shaping said article by drawing.

15. In the drawing of a ferrous metal article,

the method comprising the steps of subjecting the surface to be drawn to a ferric sulphate solution to substantially remove said surface and produce a uniform pitting thereon, subjecting said article to hydrogen sulphide in the presence of water, and subsequently shaping said article by drawing. 16. In the drawing of a ferrous metal article, the method comprising the steps of subjecting the surface to be drawn to a ferric sulphate solution, placing a drawing aid thereon which is the reaction product of hydrogen sulphide and the iron of said article, treating said coating to substantially prevent oxidation thereof, and then shaping said article by drawing.

17. In the drawing of steel ammunition components, the method comprising the steps of placing a hydrated ferrous sulphide coating on said components, and ubsequently shaping said components by drawing.

BENJAMIN F. BUTLER. EDGAR A. HIRDLER. 

